The outage that took Google offline for scores of users on Thursday was caused by a traffic routing error, the company now says. The Google outage affected users across the United States and in numerous other countries. The vast majority of Google services became unavailable, including Gmail, YouTube, Google News, and even the google.com home page.

Google Outage Explained

The so-called #googlefail was a result of misdirected traffic, Google says: Because of a system mistake, too many users were being routed through the same location.

"An error in one of our systems caused us to direct some of our Web traffic through Asia, which created a traffic jam," explains Urs Hoelzle, Google's senior VP of operations.

The error affected about 14 percent of Google users worldwide, Hoelzle estimates. Users on both coasts of the U.S. as well as in nations such as China, Australia, and France all reported problems.

"Imagine if you were trying to fly from New York to San Francisco, but your plane was routed through an airport in Asia. And a bunch of other planes were sent that way too, so your flight was backed up and your journey took much longer than expected. That's basically what happened," Hoelzle says.

Outage Apology

Google has officially apologized for the incident, calling it an "embarrassing glitch" and promising its engineers are taking measures to prevent a repeat performance.